From WO 01/30407 A1 a method for the production of hydrogels for use as wound dressings is known, by which burns or other skin injuries can be treated. In the course of the method an aqueous solution of polyvinyl alcohol, agar-agar and at least one further natural polymer is prepared. This solution is introduced at 70-80° C. into one-way plastic containers and sealed. After cooling to room temperature the samples introduced into the one-way plastic containers are irradiated and thus sterilised.
In WO 2005/103097 A1 hydrogels are described which include at least one polyvinyl alcohol star polymer. In this case the hydrogels are produced by repeated freezing and thawing of an aqueous solution containing at least one polyvinyl alcohol star polymer and optionally further components. Furthermore such hydrogels can be produced by the action of ionising radiation on an aqueous solution containing at least one polyvinyl alcohol star polymer or by a reaction of a polyvinyl alcohol star polymer in aqueous solution with cross-linking reagents.
A disadvantage of the currently known methods for production of hydrogels, in particular for wound treatment, is the costly mode of production and the problematic further processing of the hydrogels, and also the possible occurrence of chemical contaminants in the hydrogels which are cross-linked for example by a chemical reaction. Moreover hydrogel films, in contrast to fibers and fibrous structures, have a smaller surface, so that they have a lesser absorption capacity for water or aqueous solutions. Particularly when polyvinyl alcohol is used as raw material for hydrogels care should be taken to ensure that the polyvinyl alcohol has a correspondingly high degree of cross-linking, since otherwise no hydrogels but solutions of the polyvinyl alcohol in the corresponding liquid medium are formed. Consequently a high stability of the polyvinyl alcohol relative to the solubility in water or in aqueous solutions is desirable. Moreover polyvinyl alcohol and polyvinyl alcohol copolymers are distinguished by a high biocompatibility so that there is an increasing need for further embodiments of hydrogels or hydrogelling materials with polyvinyl alcohol and/or polyvinyl alcohol copolymers which are also cost-effective and simple to produce and enable problem-free further processing.